Health Department spokesman Robert Kenny said investigators were checking records and interviewing staffers in the wake of the boy's death, which came after his skull was fractured when the tank was pulled through the air by the MRI machine's powerful magnet. The hospital and the Westchester district attorney's office also are reviewing the case.
The boy, Michael Colombini of Croton-on-Hudson, died Sunday, two days after he was hit by the tank, which is about the size of a fire extinguisher. The county medical examiner's office said the boy's death was caused by blunt force trauma, a fractured skull and a bruised brain.
The medical center in Valhalla said the tank had been accidentally "introduced into the exam room" after the boy was in the magnetic resonance imaging machine and the 10-ton electromagnet was switched on.
The oxygen tank was "immediately magnetized and drawn to the center of the machine, causing head trauma to the child," the medical center said in a news release.
The boy was sedated when he was struck, the hospital said. The MRI was scheduled to check his progress after an operation to remove a benign brain tumor, which was discovered last week after he fell down at home, friends and relatives said.
"You'd think that if you had survived all of that. you'd be sort of home free," said Diana Heaton, Michael's kindergarten teacher last year. "We're all shocked and saddened by this. He was just an awesome kid who liked having fun."
Edward Stolzenberg, president and chief executive officer of the medical center, said in a statement that the hospital assumes full responsibility and "will do anything it can to ease the family's grief."
"The trauma was due to what can only be described as a horrific accident, and the entire medical center is grieving," Stolzenberg said.
An MRI generates images of the body using an electromagnet, radio waves and a computer. It is conducted eight million times each year in the U.S. to diagnose many diseases, including brain tumors, spinal disorders and heart disease. It is considered nearly risk-free, but no metal objects are supposed to be in the testing area.
Carin Grossman, a spokeswoman for the medical center, would not say who took the oxygen tank into the MRI area.
"It was brought into the area of the field of the magnet and it went through the air," she said.
In Rochester, N.Y., last year, an MRI magnet yanked a .45-caliber gun out of the hand of a police officer, and the gun shot a round that lodged in a wall.
The Westchester Medical Center, 15 miles north of New York City, has been trying to position itself as a topflight medical center. It is a major transplant center and has recently ventured into robot surgery. It suffered a setbacin March when an accreditation team caught the staff altering a patient's chart and automatically gave it a ranking that was among the lowest in the country.
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